Artificer's Grenade Launcher (3.5e Equipment)

From D&D Wiki

This also looks like the rifle although it has a wider barrel for fitting bigger things such as alchemist fire.

This weapon allows you to fire fine-sized splash weapons much further than you could throw them. As a standard action you can fire the projectile up to 110ft. It's a move action to reload, which provokes AoO's. You can fire things such as Alchemist's Fire, Frost, Spark, Acid, thunder stones, holy water, etc. Need to be proficient in the crossbow to use. Any feats related to splash-weapons apply.

Lore: Zyash, the creator of the bolt-action rifle, also wanted to fire splash-weapons much farther than he could throw them--which wasn't very far to begin with. So he went about modifying his bolt-action rifle and came up with his grenade-launcher.